In the past various schemes have been employed to fabricate and size a core for a dynamo-electric machine, and such cores have been both of the edgewise wound type and the interfacing individual lamination type. Common to the edgewise wound and lamination type core was that each had a pair of opposite end faces interconnected between inner and outer circumferential surfaces. A yoke of these past cores was bounded by the outer circumferential surface thereof, and a plurality of tooth rows interposed between the opposite end faces extended on preselected pitch axes from the yoke with the tips of the teeth, or tooth tip rows, defining the inner circumferential surface or bore of the past cores.
In one of the past core sizing schemes, the bore of the core was burnished thereby to remove burrs or the like which may have been present on the inner circumferential edges of at least some of the laminations comprising such bore, and it is believed that such a burnishing operation may have had some sizing effect on the bore of the core. However, at least one disadvantageous or undesirable feature of the aforementioned burnishing operation is believed to be that it sized only the inner circumferential surface of the core.
In another of the past core sizing schemes, a cylindric sizing rod or arbor was forced into sizing engagement with the bore of the past edgewise wound core, and since the diameter of the sizing arbor was predeterminately greater than that of the bore, both the bore and the outer circumferential surface of the core were expanded generally radially outwardly thereof. During the sizing engagement of the sizing arbor with the bore of the core, the opposite end faces of the core were compressed in sizing engagement between a pair of die surfaces on a pair of opposed dies with the die surfaces engaging the opposite end faces in their entireties, respectively. One of the disadvantageous or undesirable features of this past core sizing scheme is believed to be that the compressive force exerted by the die surfaces onto the tooth rows of the core between the opposite end faces thereof may have been of such magnitude as to have had the tendency to angularly displace the individual teeth in the tooth rows with respect to each other. At least another disadvantageous or undesirable feature of this past core sizing scheme is believed to be that the outer circumferential surface was not sized upon the expansion thereof generally radially outwardly of the core. Still another disadvantageous or undesirable feature of this past core sizing scheme is believed to be that the yoke section of such past core may have deflected axially in response to the sizing engagement of the sizing arbor with the bore of such past core resulting in core laminations having a generally curved geometry and not suitable for farther manufacturing.
In still another of the past core sizing scheme, another sizing arbor similar to that discussed above was forced into sizing engagement with the bore of the past lamination type core, and since the diameter of the sizing arbor was greater than that of the bore, both the bore and the outer circumferential surface of the core were expanded generally radially outwardly thereof, but only portions of the outer circumferential surface of the core adjacent the opposite end faces thereof were expanded into sizing engagement with a pair of sizing rings therefor. Upon the sizing engagement of the sizing arbor with the bore of the core, the opposite end faces of the core were compressed in sizing engagement between a pair of die surfaces on a pair of opposed dies with the die surfaces engaging the opposite end faces in their entirety, respectively. Further, the die faces were provided with a pair of opposed ring-shaped platforms which formed opposite annular recesses in the opposite end faces of the core adjacent the aforementioned sized portions of the outer circumferential surface thereof, respectively. One of the disadvantageous or undesirable features of this past core sizing scheme is believed to be that the compressive force exerted by the die surfaces onto the tooth rows of the core between the opposite end faces thereof may have been of such magnitude as to have had the tendency to angularly displace the individual teeth in the tooth rows with respect to each other. At least another disadvantageous or undesirable feature of this past core sizing scheme is believed to be that only a portion of the outer circumferential surface of the core was sized. And still another disadvantageous or undesirable feature of this past core sizing scheme is believed to be that the yoke section of such past core may have deflected axially in response to the sizing engagement of the sizing arbor with the bore of such past core resulting in core laminations having a generally curved geometry and not usable for farther manufacturing.
With respect to the past edgewise wound cores, one of the problems encountered during the fabrication of such edgewise wound cores involved "spring-back" of a lanced strip of ferromagnetic material edgewise wound into a plurality of helical convolutions arranged in an annular stack thereby to comprise the edgewise wound core. For instance, the lanced strip was edgewise deformed through a predetermined radius into the helical convolutions thereof defining the core; however, in response to such edgewise deformation, the helical convolutions tended to "spring-back", i.e., tended to assume a greater radius than the predetermined radius through which the lanced strip was edgewise deformed into such helical convolutions thereof. To further complicate the above discussed "spring-back" problem, lanced strips from different stock rolls of the ferromagnetic material are believed to have exhibited different degrees of "spring-back"; therefore, each time lanced strips from such different stock rolls were formed into edgewise wound cores, it is believed that the winding apparatus therefor was shut down and set up, i.e., readjusted, to predeterminately control the different "spring-back" of such lanced strips from such different stock rolls thereof. Thus, it would be desirable to, in effect, be able to ignore the "spring-back" characteristics of the various lanced strips upon the edgewise winding thereof into edgewise wound cores, and then size both the inner and outer circumferential surfaces of such core to preselected diameters therefor.